WASHINGTON — The aircraft carrier USS Carl Vinson is headed to the Persian Gulf to conduct air operations against militants in Iraq and Syria, the Navy’s top official said Tuesday.

“It’s almost there,” Secretary of the Navy Ray Mabus told reporters at a media roundtable in Washington.

The Carl Vinson, along with the rest of its strike group, will relieve the USS George H.W. Bush, which has been stationed in the Gulf since June.

In August, F/A-18 jets flying off the Bush carried out the first airstrikes against the Islamic State terrorist group in Iraq. Navy and Marine Corps aircraft have conducted about 25 percent of the more than 260 bombing missions over Iraq and Syria since the air campaign began Aug. 8, Mabus said.

U.S. officials have said that the military campaign against the Islamic State could last for years.

“We can stay for as long as we need to stay based on the normal rotation of our ships,” Mabus said Tuesday. “It is sustainable for as long as we need to be there.”

U.S. military operations in the Middle East have sometimes required several aircraft carriers to be on station in the region. Mabus said multiple carriers aren’t needed at this point, but he left the door open for more to be sent.

“Right now we can do whatever we need to do with one carrier,” but, “if there are more missions, we’ll take a look at that,” he told reporters.

Operations against the Islamic State have cost the Navy about $100 million, including weapons used and extra jet fuel burned, Mabus said. Last week, the cruiser USS Philippine Sea and the destroyer USS Arleigh Burke launched dozens of Tomahawk missiles against terrorist targets in Syria. Each Tomahawk costs more than $1 million.

The Bush and the Bataan amphibious ready group, which is also in the Persian Gulf, have been away from their home ports since February. Mabus said the Bataan won’t return home until November after it gets relieved by the Iwo Jima amphibious ready group.

Both ships’ deployment schedules have been extended to deal with the ongoing crises, following a trend that has developed in recent years. Navy officials are concerned about the wear and tear on crews and ships. To compensate, the Navy will give troops bonus pay if they’re at sea for more than 220 days.

“If the deployment goes past that, we think you should get something extra for it,” Mabus said.

The Navy boss said he understands people’s frustrations with extended deployments, but crises can’t be avoided.

“The world gets a vote,” he said, “and sometimes you’re going to have to extend.”